Rocket base fuze



Feb. 10, 1959 v. K. RAsMussEN 2,872,859

ROCKET BASE FUzE Filed may 24, 1948 4 sheets-sheet 1 I ATTORNEY Feb- 10 1959 v. K. RAsMUssl-:N 2,872,869

l BUCKET BASE FUZ-E 4 Sheets-Sheet 3 Filed May 24, 1948 INVENTOR. VOLNEY K. RASMUSSE/V BY f Q Arronnev v .mi

y Feb. 1o, 195,9

FIG

4 sheets-sheet 4 sv-l INVENTok. VOLNE Y K. RASMUSSEN BY //Q ATTORNEY ing a modification United States Patent .O

A `2,872,869 ROCKET BASE FUZE Volney K. Rasmussen, San Marino, Calif., assignor to the f United States of America as represented by the Secretary of the Navy Application May 24, 1948, Serial No. 28,952

6 Claims. 4(Cl. 102-81) This invention relates to deceleration discriminating fuzes for military missiles, more particularly, for rockets intended to be used against ships.

vAn object of the invention is to provide a projectile fuze that does not re after impact until the deceleration or negative acceleration has vfallen below a predetermined value. Y

I, Another object of the invention is to provide a projectile, Vfuze which does not lire upon impact with a surface Y offwater but tires.k eithernpon striking a solid object or upon losing the velocity required to penetrate such an object. I

Y A `further object of the invention is to provide a rocket fuze which is armed by the gas pressure generated in the rocket motor during ight.

An additional object of the invention is to provide a rocket fuze inherently safe and foolproof at all times prior to actually firing the rocket motor.

',Another object of the invention is to provide a projectile'fuze suitable for use against a wide variety of targetsby reason of automatically; delaying the detonation of the projectile until the optimum penetration of the target has occurred.

An Vadditional object of the invention is toprovide a rocket fuze whichis especially effective underwater against submarines or therhulls of surface vessels by reason of arming in flight, cocking upon impact with Vthe water surface, and tiring when the deceleration drops below a selected value. Y

.Other objects of the invention Vwill becomeapparent upon study of the accompanying drawings and descriptions Awhich set forth the preferred embodiment of the many modiiications and adaptations of which the invention is capable.

In the drawings:

Fig. 1 is a longitudinal section of thevfuze in the unarmed condition.

Fig. 2 is a transverse section of the fuze in the same condition, taken on line 2 2 of Fig. l.

.Fig.'3 is al longitudinal section view of the fuze in the same-condition taken on the line 3 3 of Fig. 2.

,FigQ 4 is a View similar to Fig. l showing the fuze of the invention in flight in the armed but uncocked condition. s

Fig. 5 is a fragmentary sectional view taken on the 'same `plane as Fig. 1 showing the fuze in the -armed and cocked condition uponimpact or rapid deceleration.

Fig. 6 is a view -similarto Fig. 5 showing the fuze of the invention at the time of tiring.

Fig.` 7 is a fragmentary longitudinal section view showof the firing pin and detonator asse'mbly.

AReferring to Fig.'. 1 of the drawings, the yfuze mechanis'm'is'contained in'fuz'e body 11 which is installed in the base, of a rocket head or projectile (not shown). The right or forward end of the body 11 is in contact with the` bursting charge of the rocket head. The left or rear ward end of fuze body 11. A magazine cover 48 of any Y 2 end of the body 11 is exposed tothe combustion chamber of the rocket motor (not shown).

The base of the fuze contains the two pressure chambers 12 and 13 formed by the plug 14, the baffle cup 15 which has a small oriiice 16, and the diaphragm 1'7. Gases from the combustion of the propellant in the rocket motor, which are utilized in arming the fuze, enter these chambers through the inlet valve 1S. The gases are admitted through inlet valve filter 19 of meshed Inconel wire which lters out any solid matter carried by the products of combustion. After passing through passage 20, the gases impinge on the inlet valve ball 21 forcing itforward olf its seat and compressing the inlet valve spring 22, thus permitting the gas to slowly enter the first pressure chamber 12. From outer pressure chamber 12, the gas ows to inner pressure chamber 13 through orifice ,16 which is of smaller diameter than inlet passage 20. The diaphragm 17 seals ol the remainder ofthe fuze body cavity. This diaphragm is made from any suitable exible and impermeable material, and it is backed with a reinforcing disc 23 to strengthen its central portion.

1 Immediately forward of diaphragm 17 an arming sleeve 24 is iixed to a stationary retaining cup 25 by a shear Wire`26. The retaining cup is held in position against longitudinal movement by'a bearing ring 27 abutting a shoulder in the fuze body cavity and the threaded retainer ring 28, and anchored against rotary movement by the locating pin 29 which ts into a slot in the retaining cup, A pin 29 extending diametrically through thearming sleeve 24 engages longitudinal interior slots 31 in the rotor 32 which is spring-loaded by a torsion spring 33. The rotor slots 31 also engage the detonator plunger pin 34 which passes through the detonator plunger 35. Located in a longitudinal plane, perpendicular to the plane of Fig. 1 are two pins 36 xed in the rotor and slidably engaging the holes 37 in the trigger block 3S. A tiring pin 39 loaded by the compressed helical iiring pin spring 40 is contained within the detonator plunger 35 and held cocked `by several lock balls 41 which are retained in holes in the detonator plunger by trigger block 38. For a view of rotor pins 36, see Fig. 4.

Screwed into the forward end of the detonator plunger 35 is a detonator case 42 containing a percussion primer 43, a 0.010-second black powder delay element 44, a relay detonator 45 and tetryl lead-outs 46 (see Fig. 4). In the unarmed position (Fig. l) these lead-outs are so oriented that the detonator plunger assembly must be rotated to the armed position (Fig. 4) and also moved forward (Fig. 5) to line up the lead-outs with the lead-ins 47. These lead-ins are passages of circular cross section disposed radially and longitudinally in the forsuit'able material is screwed onto the end of the fuze body and contains the tetryl booster pellet 49 which i-s in close proximity with the forward ends of the lead-ins 47.

In lassembling the fuze, the locating pin 29 serves to orient the entire interior assembly. The forward end of the detonator plunger 35 is slotted in such manner that in the unarmed position, the detonator plunger is constrained from moving forward by the solid portions of the.

end of the detonator plunger bearing against the fixed stop pins 50 in the side of the fuze body asshown in Fig. l. In arming the fuze, the detonator plunger 35 is rotated approximately 90 by torsion spring 33, bringing the slots 51 (Fig. 4) into engagement with the stop pins, thereby permitting the detonator plunger to move forward under the influence of inertia 'until the forward end of the detonator plunger reaches the shoulder 52 in` i the fuze body. Y As shown in Fig. 5, when the detonator.

plunger reaches this position, the radially disposed springmounted detents 53V move inwardly and engage a shoulder on the detent plunger 35 to prevent it from moving to the rear.

The trigger spring 54 is compressed between the trigger latch 55 and the shoulder 56 on the trigger block 38. Trigger latch .balls 57 bearing against the detonator plunger 35 and a groove in the trigger latch 55 lock this latch with respect to the trigger block 38.

Referring to Figs. 2 and 3, it will be seen that a portion of the rotor 32 has been cut away in order to cooperate with rotor stop pin 5S mounted in retaining cup 25 to limit the motion of the rotor to approximately 90. It will be obvious that the t of the rotor must be adjusted to permit free rotation with respect to all other elements except rotor stop pin 58.

Another modification of the invention is illustrated in Fig. 7 which is a fragmentary view of the fuze in the same position as in Fig. 5. Here, an instantaneous firing train has been substituted for the delayed-action train of Fig. 5. This modification utilizes a ring'pin 139 with a sharp point, a stab-type sensitive primer 143 and omits the delay element 44 (Fig. 5). All other members are identical with those disclosed in Figs. l' to 6.

The operation of the fuzes of the invention involves the steps of arming, cockiug and firing. The fuze is armed by gases from the rocket motor entering through inlet valve filter 19 and inlet passage 20, forcing the inlet valve ball 21 forward olf its seat and compressing the inlet valve spring 22. This permits the gases to slowly enter the first pressure chamber 12. The gases then ow more slowly into the inner pressure chamber 13 through a smaller oricel in the baille cup i5. When therpressure in the inner chamber reaches a selected value, such as approximately 525 pounds per square inch, diaphragm 1! is pushed forward, forcing the arming sleeve 24 forward and shearing the shear wire 26. This frees the arming sleeve 24 as well as the rotor 32 which the arming sleeve engages by means of the arming sleeve pin 30, and permits the loaded torsion spring 33 to turn the rotor 32 approximately 90. The rotor, which also engages the detonator plunger pin 34 and the trigger block 3S (by means of the rotor pins 36), thus turns the detonator plunger-trigger block assembly 90 until the rotor is stopped by the rotor stop 58 in the stationary retaining cup 25, lead-outs 46 in the detonator case are then lined up radially with the lead-ins 47 in the fuze body, but are still offset with respect to them along the fuze axis. Slots 5l in the end of the detonator plunger 35 and stop pins 50 are also aligned by the rotation so that the detonator plunger-trigger block assembly is free to move forward under the action of creep force (that is, the relatively small inertia force produced by air resistance slowing down or decelerating the exterior of the rocket projectile) until the forward end of the trigger block 3S rests against the shoulder 59 in the fuze body. Thus the arming operation involves the steps of rotation of the detonator plunger-trigger blockassembly and movement of this assembly forward by creep force to the position shown in Fig. 4 Where the slots 51 in the detonator plunger 35 engage the stop pins 50. When this operation is completed, the fuze is ready to either be cocked by light impact or be cocked and fired upon heavy impact. When cocked by a light impact, as for example on the surface of water, the fuze is then ready to tire when thedeceleration or negative acceleration ofthe projectile drops below a'` preselected value regardless of whether the projectile is slowedi down gradually by travel underwater or slowed rapidly by striking a solid object.

Friction of the four ring pin lock balls 41' on `the trigger blocky 38 prevents the cletonator'plunger from moving farther forward than shown in Fig.- 4 until impact. If" necessary; thev trigger block mayv be'constructed with a shallowl shoulder'on its interior at/ the forward end in order toV increaseY its frictional engagement with the ring pin lock balls. Upon impact the detonator plunger moves forward to the position shown in Fig. 5 where it is stopped by the shoulder 52 in the fuze body adjacent to the lead-outs 46, and is locked in this position by the detents 53; this cocks the fuze. In this position the leadouts in the detonator case 42 are aligned with the leadins in the fuze body. Simultaneously, the trigger latch balls 57 fall in behind a sloping shoulder of the detonator plunger 35, releasing the trigger latch 55 which was formerly locked to the trigger block 38 thereby rendering the trigger spring 54 potentially active. The trigger spring is then effectively compressed between the shoulder 56 on the trigger block and the trigger latch resting against shoulder 59 in the fuze body cavity.

As long as the deceleration of the round is high, the inertia of the trigger block keeps the trigger spring compressed; but as soon as the deceleration drops below a predetermined value, the spring overcomes the inertia and frictional resistance and pushes the trigger block to the rear. This releases the liring pin lock balls 41 to move outward into the annular space now provided directly in front-of the trigger block and release the springloadedY firing pin 39. Firing pin spring 40 immediately drives the tiring pin into the percussion primer 43. This primer is set olf and in turn fires the delay element 44 which detonates the relayl detonator 45 0.010 second later. The relay detonator lires the lead-outs 46 which in turn set olf the lead-ins 47 which tire the booster pellet 49 to detonate the bursting charge in the projectile. The position of the various elements of the fuze at the instant of firing is shown in Fig. 6. y

In the modification illustrated in Fig. 7, the action is the lsanne except that no delay is introduced. Pointed tiring pin 139 is driven into and sets off the primer 143 which in turn immediately fires the relay kdetonator 45. After that the sequence of actions in the firing train is identical with that described in conjunction with Fig. 6.

The value of deceleration or negative acceleration which will tire the fuze depends on several factors. One is the mass or weight of the trigger block which determines the inertia force acting against the trigger spring for any given deceleration. Another is the strength of the trigger' spring. A third of these factors is the smoothness of the surfaces of the trigger block and associated parts, as the friction resistance to rearward motion depends on this. Various deceleration values may be' selected according to the type of missile and the typefof target. As an example, values ranging from approximately 45 to 75 times theV acceleration of gravity are preferred for underwater-stable rocket projectiles for use' against hostile ships.

The time required for the gas pressure in the inner pressure chamber 13 to reach the arming pressure value of 525 lbs. per sq. inch is dependent upon the pressure' of the propellant gases in the rocket motor which in turn depends on the initial temperature of the solid propellant material. As soon as the burning of the propellant has ceased, the inlet valve spring and ball close the inlet passage 20, trapping the gases in the fuze pressure cham bers. #Since at this point the pressure is higher in the outer chamber 12 than in the inner chamber 13, the pressure in the inner chamber continues' to rise until' the pressures in both chambers are equalized. Thus, if the propellant is consumed before the arming pressure isv attained' in the inner chamber, closing of the inlet valve will permit arming to bel accomplished after the end' of the normal burning period of the propellant. The gals pressure required for arming depends on the strength of the 'shear wire, the effective area of the diaphragm, and. to some extent in the t of the arming sleeve with asso'- ciated members; consequently the necessary pressure may be selected by proper selection of these factors.

It should be understood that theabove descriptionconstitutes only the preferred embodiment of the invention, but that it is capable of a wide variety of modifications and adaptations and that the invention is limited only by the true and proper scope of the appended claims.

I claim:

1. In a fuze, pressure operable arming means releasably and rotatably supported within said fuze for movement from an initial safe position to an armed position when released, means for rotating said arming means to said armed position as the arming means is released, means including a pressure responsive device for releasing said arming means as the device is moved a predetermined amount in response to a predetermined pressure applied thereto, means for cocking the fuze upon rapid deceleration, pressure means, means including an inertia member operable to detonate the fuze`at predetermined reduced deceleration as the inertia member is moved by said pressure means in response thereto. y Y

2. In a fuze, a fixed explosive train, a movable detonation traininitially'remote from the fixed train, arming means releasably and rotatably supported within said fuze for aligning the detonation train and the fixed train in one plane as the arming means as rotated a predetermined amount, means for rotating said arming means said predetermined amount, means including a pressure responsive device for releasing said arming means as the device is moved a predetermined amount in response to a predetermined pressure applied thereto, a locked pressure member, cooking means loperable upon rapid demaintaining the locking means in engagement with the celeration-to free the pressure member and to align the Y detonation train and iixed trainlin a second plane,V a locked firing pin, a primer at one end of thedetonation train, means for propelling the firing pin into the primer, and an. inertia member movable by the pressure member at a predetermined reduced deceleration to release the tiring pin, whereby the firing pin strikes the primer to set ott the detonation train which tires the fixed explosive train in turn.

3. In a deceleration discriminating fuze for military missiles, a ixed explosive train, a movable detonation train initially remote from the xed train, arming means releasably and rotatably supported within said fuze for radially aligning the detonation train with the xed train as the arming means is released and rotated a predetermined amount, means operatively connected to said arming means for rotating the arming means said predetermined amount as the arming means is released, means including a device slideably arranged Within the fuze for releasing said arming means as the device is moved a predetermined amount, pressure controlled means movable into engagement with said device in response to a predetermined pressure applied thereto for moving said device said predetermined amount, a compressed and locked trigger spring, cooking means operable upon rapid deceleration to free the trigger spring and to longitudinally align the detonation train with the fixed train, a locked and spring loaded tiring pin, a primer at the end of the detonation train adjacent the tiring pin, and a trigger block movable by the trigger spring against the force of inertia tiring pin; a trigger spring engaging the block; trigger latch means holding the trigger spring compressed; an arming sleeve; a shear wire fastening the sleeve to the body; a rotor rotatively engaging the sleeve, the plunger and the block; a torsion spring under tension engaging the rotor; a pressure chamber in the body; a exible permeable diaphragm adjacent one end of the sleeve and forming one wall of the chamber; and an inlet valve in a wall of the chamber connected to a rocket motor; whereby the fuze is armed by propellant gases under pressure entering the chamber through the valve forcing the diaphragm against the sleeve to shear the shear Wire thereby freeing the rotor to turn the plunger to radially align the detonation train with the xed train and to free the plunger for longitudinal movement, the uzc is cocked by rapid deceleration moving the plunger to longitudinally align the detonation train with the fixed train and to release the trigger latch means, and the fuze is detonated at a predetermined reduced deceleration by the trigger spring overcoming the reduced inertia force of the trigger block to move the block to release the ring pin to set ol vthe detonation train to tire the iixed explosive train.

5. The fuze of claim 4 in which the detonation train includes a delay element and the trigger block and trigger spring are so constructed and arranged as to detonate the fuze when the deceleration is reduced to between 45 to 75 times the acceleration of gravity.

6. The fuze of claim 4l in which the detonation train consists of substantially instantaneouselements and the trigger block and trigger are so constructed and arranged as to detonate the fuze when the deceleration is reduced to between 45 and 75 times the acceleration of gravity.

References Cited in the tile of this patent UNITED STATES PATENTS 682,728 Lynch Sept. 17, 1901 1,545,139 Greenwell July 7, 1925 2,145,507 Denoix Jan. 31, 1939 2,378,626 Fanger June 19, 1945 2,441,897 Nichols May 18, 1948 2,443,041 I ordan June 8, 1948 l FOREIGN PATENTS 110,915 Great Britain Nov. A6, 1917 

